Brush actuating means for dynamo electric machines



Jan. 26, 1932. e. A. WATERS 1,842,773

BRUSH ACTUATING MEANS FOR DYNAMO mxmuc MACHINES Filed Jan. 26, 1929 -n Fig.1. 9

3 IO M Inventor V c. A. WAT ERS Att'y.

Patented Jan. 26, 1932 UNITED STATES PATENT OFFICE GRANVILLE A. WATERS, OF ST. LOUIS, MISSOURI, ASSIGNOR TO WAGNER ELECTRIC CORPORATION, OF ST. LOUIS, MISSOURI, A CORPORATION OF. DELAWVARE BRUSH ACTUATING MEANS FOR DYNAMO ELECTRIC MACHINES Application filed January 26, 1929.

My invention relates to brush actuating means for dynamo electnc machines and lts object is to prevent or materially decrease noise resulting from brush vibrations. In the drawings I have shown it applied to a motor of the repulsion-induction type, provided with a vertical face commutator and with centrifugal means for moving the brush holder to bring the brushes out of engagement with the commutator when a predetermined speed has been reached. Machines of this type are commonly used under such service condition that the brushes must have a relatively loose fit with the holder slots in order that they may not bind, due to accumulation of dirt, and also, for mechanical reasons, it

' is not desirable to so design the brush holder moving mechanism that the holder is to be closely adjacent to the commutator in its position in which the brushes are in service to start the motor. The conditions just re ferred to permit the action of the commutator on the brushes to set up a vibration of the brushes against the holder and produce a chattering noise which is Very objectionable, particularly in machines for household 7 service.

, of any parts in addition to those ordinarily employed.

In the drawings Figure 1 is a cross-sectional view showing a well known type of brush holder and mechanism for actuating it employed in machines of the repulsioninduction type, and my improved means for applying advancing and guide contact pres sure to the brushes; Figure 2 is a top plan view of the brush holder of Figure 1, also showing a brush. in one of the brush guides and a top view of the brush actuating finger or follower; Figure 3 is a side elevational view of the holder-arm and associated parts shown incross-section in the upper part of Figure 1; and Figure 4 is a view illustrat- Serial No. 335,303.

construction has no relation to my invention,

it will not require a detailed description. The brush holder 1 is mounted on the hub 2 forming a part of the end plate 3 of the machine, and is moved by centrifugal mechanism, not shown, to bring the brushes out of contact with the commutator when a predetermined speed has been reached. This centrifugal mechanism acts through rods 4 to move the collar-5 to the left against the action of the spring 6, and to also move the brush holder in a like direction, thus moving the brushes out of contact with the commutator and bringing the centrifugally actuated commutator short circuiting elements 7 into cooperative relation with the segments of the commutator 8. lVhen the motor is not running, or running below the predetermined speed, the spring 6 holds the brush holder in its operative position shown in Figure 1. The brushes 12, one of which is shown in each figure, are slidably carried in the guide slots in the holder arms.

Referring now to the means constituting one embodiment of my invention for preventing noise resulting from motion of the brushes imparted by commutators in prior constructions of brush holders, the brush follower 9 is pivotally supported on extensions 10 of the arms of the brush holder and is actuated by the spring 11 to apply an advancing pressure to the brush to maintain it in proper pressure contact with the commutator, and to secure the object of my invention I so form the brush contacting face of the follower that it contacts only with a corner of the brush and extends in a direction at an angle to the perpendicular to the longitudinal axis of the brush slot. This relation is achieved in the structure shown in the drawings in which the pivot of the follower 9 is at right angles to the axis of the brush guide, by twisting the brush contacting end of finger. As will appear from Figure 4, the angular relation of the contacting portion of the finger to the brush results in a tendency for the brush to assume and be held in the position shown in which at one side itcontacts with the upper part of the wall of the guide and at the other side contacts with a lower part of the wall of the guide, and is thus prevented from vibrating against the guide walls. This elimination of brush vibration by holding it in pressure engagement with parts of the walls of the guide, eliminates the major portion of noise which has, in prior construct-ions, resulted from the effects of the rotational contact of the commutator with the brush.

It will be understood that the brushes may be held in lateral pressure engagement with the walls of the guide by means of fingers so pivoted as to move at an angle to the axis of the guide, but the particular embodiment of my invention illustrated in the drawings is preferable from the standpoint of manufacture and assembly of the holder and with this form the amount of lateral pressure on the brush may be readily adjusted without undue affect on the contact pressure produced etween the brush and the commutator.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

In a dynamo eleetric machine, the combination of means forming a brush guide passage, a brush longitudinally movable therein, and a brush advancing finger, pivotally mounted to rotate in the plane of motion of the brush, said finger having a lower face extenning at an angle to the perpendicular to the plane of motion of the brush and contacting with the outer end of the brush at one corner thereof, said finger being bendable to vary the angle of said brush containing face.

In testimony whereof, I hereunto affix my signature, this 22 day of January, 1929.

' GRANVILLE A. WATERS. 

